Swinging bucket centrifuge rotor

ABSTRACT

A swinging bucket centrifuge rotor made of separate, modular parts which are releaseably assembled and secured firmly in position by threading engagement between a nut and a central support block.

United States Patent Filz 1451 May 30, 1972 [54] SWINGING BUCKET CENTRIFUGE 2,878,047 3/1959 Booth ...308/DIG. 7 ROTOR 2,878,994 3/1959 Anderson ..233/26 3,081,029 3/1963 Gauslaa 1 ..233/26 [72] 3,468,474 9/1969 Shoblom et al. ...233/26 x 73 A' :I SollI.,Nwt,C 1 sslgnee v n M M 6 FOREIGN PATENTS OR APPLICATIONS [22] Filed: Oct. 20, 1969 219,057 2/1910 Germany ..233/26 [21] Appl No.: 867,566

Primary Examiner-Jordan Franklin 52 us. (:1 ..233/26 Assisi! Emmi'wrG99rse Krizmanich 51 1 1111. C1. ..B04b 9/12, B04b 9 14 Arwrneyl- Jordan Kunik [58] Fleld of Search ..233/26; l64;287;289;290/;

308/D1G. 7 ABSTRACT A swinging bucket centrifuge rotor made of separate, modular [56] References Cited parts which are releaseably assembled and secured firmly in UNITED STATES PATENTS position by threading engagement between a nut and a central support block. 581,188 4/1897 Wickson.. ..233/26 2,110,308 3/1938 Nelson ..233/26 X 5 Claims, 4 Drawing Figures PATENTED MAY 3 0 m2 SHEET 10F 2 PATENTEDMAH I9 2 3,666,171

SHEET 2 OF 2 mv TOR (644/9155 fl/zz ATTORN EY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to centrifuges and, more particularly, to a swinging bucket centrifuge rotor made of simple modular parts that can be readily assembled and disassembled, and readily mounted upon and removed from a rotor shaft. The rotor comprises a pair of separate, identical rails, a pair of trunnion rings, and a central support block which are readily assembled and disassembled by means of the cooperation of these parts with a clamp plate and a nut threadably engaging said block. The pivotable trunnion rings removably accommodate test tubes or buckets in which materials to be centrifuged are placed. The respective modular parts are interchangeable with each other and are formed in such a manner that by the tightening of a threaded nut on the central support block, the parts are secured to each other into a sturdy assembly that can withstand high centrifuging speeds. Beveled mating surfaces are formed in adjacent components which cooperate to exert ultimate vector forces between said component parts upon the tightening of the threaded nut which forces said component parts into a rigid assembly that ensures safety of centrifuging operation. The assembly and disassembly of the centrifuge rotor requires a minimum of handling skill, and enables dismantling of the apparatus for thorough cleaning and sterilization of the parts, especially when the rotor is to be used in biological and clinical research and processing.

2. Description of the Prior Art Amongst the prior art of which applicant is aware are U.S. Pat. Nos. 987,811; 1,001,611; 1,495,923; 2,202,157; 2,351,708; 2,604,261; 2,820,590 and 3,028,075. None of these patents disclose assemblies of separable modular parts that are in any way comparable to the structure of the present invention. Some of the prior art swinging bucket rotor assemblies are costly to manufacture and cannot be readily disassembled for cleaning and replacement purposes. Also, the rotor portion of some of the rotor art structures are weakened by mounting apertures whereby the width or thickness of the rotor must be increased by the dimension of the mounting aperture in order to provide sufficient strength to withstand centrifuging forces. Furthermore, in other prior art structures, the rotors have irregular vertical or horizontal profiles whereby at the areas of curvature or irregularity of said profiles centrifuging stresses tend to weaken the structural integrity of the rotor.

SUMMARY OF THE INVENTION The invention herein overcomes the foregoing and other disadvantages of the prior art by providing an assembly of modular structural parts comprising a substantially parallel spaced apart pair of rotor rails that are essentially regular in profile so as to obviate any possibilities of weakness therein that might otherwise subject the rotor to fracture under centrifuging stresses. The two rails have centrally located recesses which are engaged intimately into a mounting block structure which, in effect, rebuilds those recesses into a virtual unitary rail structure so that the rails are fortified against longitudinal centrifuging stresses. The central support block combines with the central portions of the rails to form a virtually solid structure which is uninterrupted by any mounting holes so that the physical soundness of the rails is preserved.

Furthermore, the swinging bucket trunnions that are pivotally mounted at the respective ends of the pairs of rails are disengaged when the rails are released from the mounting block so that all of the separate modular parts of the centrifuge rotor and the trunnion rings may be readily cleaned and reassembled.

Also, by providing that each of the component parts comprising rotor rails, trunnion rings, and mounting block elements are identical in size, it is evident that the centrifuge can be produced accurately with a minimum of machine operation and tooling, thereby reducing the cost of the centrifuge.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a broadside elevation of the apparatus of the present invention;

FIG. 2 is a top view of the apparatus shown in FIG. 1, some parts being broken away and some parts in dotted outline;

FIG. 3 is an enlarged fragmentary section view taken on line 3-3 of FIG. 2, some parts being shown in elevation; and

FIG. 4 is an exploded perspective view of the apparatus shown in FIGS. 1, 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in detail, there is shown a base 11 which supports an upwardly extending shaft 12 rigidly mounted therein. Base 11 and shaft 12 are utilized in connection with the centrifuge rotor disclosed herein for the purpose of preparing chromatography materials for tests and experiments by means of centrifugation in the rotor of the present invention. Shaft 12 is also representative of a rotatable element which is attached to a suitable source of rotating power such as an electric motor or the like, not shown, for centrifugally rotating the rotor.

The centrifuge rotor, generally designated 14, comprises a pair of parallel, spaced apart, identical elongated rotor rails 16 and 17, each of said rails having at or near their respective ends bearing apertures 18 and 19 which pivotally accommodate pins 20 and 21 which extend outwardly in opposite directions from a pair of identical trunnion rings 22 which are freely pivotable between rails 16 and 17.

Formed centrally between the respective ends of rails 16 and 17 and facing outwardly therefrom are upper and lower beveled longitudinal recesses 23 and 24, respectively. A generally cube shaped central support block 26 has a vertical axial aperture 27 slidably accommodating the upper portion 28 of shaft 12, said portion 28 being of slightly reduced diameter to form an annular support ledge 29 located at the juncture therebetween. The bottom portion of block 26 has a pair of integrally formed support arms 31 extending laterally in opposite directions therefrom, said arms each having upwardly extending sloping retaining walls 32 which mate with recesses 24 in rails 16 and 17. Also, block 26 has vertical walls 33 against which the inner walls of rails 16 and 17 bear.

Integrally formed on the top surface 34 of block 26 is a centrally located, upwardly extending threaded annular collar 36. The upper end of collar 36 has a pair of downwardly extending recesses 37 which are located apart in said collar. Recesses 37 freely accommodate and support a pin 38 which also is freely nested within a diametrical recess 39 in the top end of portion 28 of shaft 12. Thus, the rotation of shaft 12 causes the rotation of block 26 by mutual engagement with pin 38.

MOunted upon and extending over the intermediate portions of both rotor rails 16 and 17 is a horizontal clamp plate 41 having a central circular aperture 42 through which collar 36 extends freely and upwardly. Clamp plate 41 has a pair of integrally formed, downwardly extending identical arms 43, the bottom portions of which have sloping surfaces 44 which mate with respective upper beveled recesses 23 of rotor rails 16 and 17.

Located above clamp plate 41 is an internally threaded circular nut 46 which threadably engages collar 36 to urge plate 41 downwardly upon rotor rails 16 and 17, and urges the latter downwardly upon block 26 whereby all of said component parts are firmly secured together by the action of the respective beveled and sloping mating surfaces 23-44 and 24-32. Said mating surfaces are machines to sufficiently fine tolerances whereby the component parts fit precisely together and securely when nut 46 is threadably tightened down upon plate 41. When said component parts are secured firmly in position by the tightening of nut 46, this action also causes trunnion rings 22 to be secured pivotally in position whereby they may undergo the action of centrifugal force and still be retained between rotor rails 16 and 17.

In some embodiments, mating beveled surfaces 23-44 and 24-32 are formed preferably at an angle of approximately 45 from adjacent component surfaces. The action of tightening the nut 46 ensures that rails 16 and 17 will be urged firmly and retained securely against the respective vertical walls 33 of block 26 which is made of a sturdy block of steel, aluminum, or other suitable metal alloy. In other embodiments, the angle of incidence of said respective mating surfaces may be varied somewhat from 45 to accommodate manufacturing and design requirements.

It will be noted in FIG. 3 that the top surface 34 of block 26 is lower than the upper surfaces of arms 16 and 17, providing a clearance 53 whereby plate 41 is permitted to bear down without hindrance upon both rails 16 and 17 to form a secure assembly of all of the components without obstruction of such action by block 26.

At the lower end of aperture 27 of block 26, an annular beveled surface 54 mates with annular shoulder 29 on shaft 12 whereby said block and the components of the rotor are removably supported on said shaft. The inner surface 27 of block 26 mates with the outer surface of shaft portion 28 by means of a close tolerance sliding fit. In FIGS. 1 and 3, shaft 12 represents a stationary mounting element for use when the operator of the apparatus performs processing procedures in connection with tubes 47, in which case the annular shoulder 29 on said shaft serves to support the rotor thereon. When the rotor is mounted, however, on a centrifuge drive shaft as exemplified by shaft 12a (FIG. 4), annular shoulder 29 is omitted and said shaft is of uniform diameter since the rotor is then supported by pin 38 nested in recess 39 on the upper end of said shaft.

Inserted through the central aperture of each ring 22 and extending downwardly therefrom is a bucket or tube 47, each of said tubes having at its open upper end an integrally formed flange 48 extending radially over a portion of the top of ring 22 whereby said tube 47 is suspended both while rotor rails 16 and 17 are at rest, and while under centrifugation when trunnion rings 22 rotate on their respective pivot pins and 21.

Although in some embodiments pins 20 and 21 may be mounted by close tolerance sliding fit directly within bearing apertures 18 and 19 in rails 16 and 17, respectively, without any intermediate bearings, it is desirable in some embodiments to provide suitable bearings which will ensure substantially friction-free rotation of trunnion rings 22 during centrifugation. Accordingly, pins 20 may be provided with sleeve bearings 51 made of filled Teflon or other suitable low friction material, said bearings being interposed between pins 20 and 21 and apertures 18 and 19 of rotor rails 16 and 17, respectively. Sleeve bearings 51 may also provided with integrally formed, inner annular flanges 52 which are interposed between adjacent walls of ring 22 and facing respective inner walls of rotor rails 16 and 17, thereby minimizing friction between said rings and said rotor rails.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifcations can be substituted therefor without departing from the principles and true spirit of the invention.

I claim:

1. A swinging bucket centrifuge rotor comprising a pair of spaced apart, substantially parallel identically formed elongated support rails, a pair of trunnion rings, first means for pivotally and freely releasably securing a trunnion ring between the respective end portions of both of said rails, a block positioned between intermediate portions of said respective support rails, an upper and lower beveled recess on each support rail intermediate the ends thereof, a beveled support arm on each of the opposite sides of said block cooperating with said lower beveled recesses of both rails, a clamp plate removably mounted on said block, a pair of beveled surfaces on said clamp plate cooperating with the respective upper beveled recess of each of said rails, and second means urging said clamp plate against said block whereby said support arms, surfaces and respective beveled recesses cooperate to cause said support rails to be urged firmly against and locked in position relative to said block.

2. A rotor according to claim 1 and further comprising an integrally formed threaded annular collar on said block and a nut cooperating with said collar to urge said clamp plate into a locking position against said block.

3. A rotor according to claim I and further comprising an annular threaded collar on said block, a rotatable shaft upon which said block is removably mounted, a recess extending across the top of said shaft, a pair of recesses at the top of said collar, a pin freely removably inserted into said shaft recess and said collar recesses when all of said recesses are aligned and a nut threadably engaging said collar to cause said pin to be held captive in said recesses whereby the rotation of said shaft operates through said pin to cause the rotation of said block and said support rails.

4. A swinging bucket centrifuge rotor comprising a pair of identically formed elongated support rails, a separate mounting block located between the central portions of said support rails, a removable clamp plate on said block, cooperating angled surfaces on said rails, on said block and on said clamp plate, and a threaded element releasably securing said clamp plate on said block whereby said respective angled surfaces cooperate with each other to urge said rails into firm and secure engagement with said block in a spaced apart substantially parallel array.

5. A rotor according to claim 4 and further comprising a trunnion ring for each end portion of said pairs of rails, means on said rings and means on the ends of said rails cooperating with each other for releasably securing said ring between said rails when said clamping ring and said block engage said rails and are secured in position. 

1. A swinging bucket centrifuge rotor comprising a pair of spaced apart, substantially parallel identically formed elongated support rails, a pair of trunnion rings, first means for pivotally and freely releasably securing a trunnion ring between the respective end portions of both of said rails, a block positioned between intermediate portions of said respective support rails, an upper and lower beveled recess on each support rail intermediate the ends thereof, a beveled support arm on each of the opposite sides of said block cooperating with said lower beveled recesses of both rails, a clamp plate removably mounted on said block, a pair of beveled surfaces on said clamp plate cooperating with the respective upper beveled recess of each of said rails, and second means urging said clamp plate against said block whereby said support arms, surfaces and respective beveled recesses cooperate to cause said support rails to be urged firmly against and locked in position relative to said block.
 2. A rotor according to claim 1 and further comprising an integrally formed threaded annular collar on said block and a nut cooperating with said collar to urge said clamp plate into a locking position against said block.
 3. A rotor according to claim 1 and further comprising an annular threaded collar on said block, a rotatable shaft upon which said block is removably mounted, a recess extending across the top of said shaft, a pair of recesses at the top of said collar, a pin freely removably inserted into said shaft recess and said collar recesses when all of said recesses are aligned and a nut threadably engaging said collar to cause said pin to be held captive in said recesses whereby the rotation of said shaft operates through said pin to cause the rotation of said block and said support rails.
 4. A swinging bucket centrifuge rotor comprising a pair of identically formed elongated support rails, a separate mounting block located between the central portions of said support rails, a removable clamp plate on said block, cooperating angled surfaces on said rails, on said block and on said clamp plate, and a threaded element releasably securing said clamp plate on said block whereby said respective angled surfaces cooperate with each other to urge said rails into firm and secure engagement with said block in a spaced apart substantially parallel array.
 5. A rotor according to claim 4 and further comprising a trunnion ring for each end portion of said pairs of rails, means on said rings and means on the ends of said rails cooperating with each other for releasably securing said ring between said rails when said clamping ring and said block engage said rails and are secured in position. 